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cditzen 06-14-2001 11:32 AM

Boom Preventer or Not?
Hi there,

I am wondering about the pro''s and con''s of using a preventor. We own a 40footer, which we race quite a bit. So far, we''ve never used a preventor, since it would be just one more line to deal with during gybes, which are hassle enough with a dip-pole chute set-up.

Recently, we did an overnight race (SF to Monterey). It being a run nearly all the way, we were flying the chute. It was blowing about 16-20kn, and during an accidental gybe at 1:00AM (swells on the quarter) we wrapped the mainsheet around the binnacle and tore it off the cockpit floor. Pretty scary stuff. We recovered, hooked the emergency tiller up, stopped flying the chute, and continued on.

Anyhow, after the race, this brought up a lively discussion about whether to use a preventor or not, with the crew about evenly split. I am in general on the ''not'' side, hating the thought of what a preventor would do during a broach, etc.. Any thoughts?


jack_patricia 06-14-2001 11:55 AM

Boom Preventer or Not?

This is a great question, and falls inside the general territory of ''When is a safe practice or safety gear unsafe...?''

Just a clarification, so we''re talking the same language. A preventer typically refers to a line run forward from the boom end (or nearly so) to the foredeck somewhere, and then perhaps/perhaps not back to the cockpit. It''s purpose is to prevent an accidental jibe & the damage it may cause (such as your experience). A boom vang can run from the mid-boom area to the sidedeck (and maybe back to the cockpit), and is intended to flatten the mainsail on a reach/run. OR these days, can be an in-line vang of some kind, tacked to the mast base and would do ''zip'' re: a jibe. IOW it''s a trimming device, tho'' it may/may not serve partially as a preventer.

I''m guessing that you made your initial decision (not to hook up a preventer) based on your normal racing/sailing experiences, which I''m betting are on the Bay. Then you found yourself offshore in more swell & boat motion than your crew typically faces, and the sea contributed to the jibe. Or put in the form of a question, did you make your ''no preventer'' decision based on Bay racing but find yourself in seas that more typically would call for one?

Another question is whether you have a boom vang and/or boom brake on the boat? I''d expect at least the former on a racing boat, but if it''s an in-line vang (vs. taken to the side deck) that''s irrelevant to your question re: a preventer.

FWIW some form of preventer can be a good fundamental practice offshore, especially when short-handed - at least, when sailing conservatively. Racing is a different ballgame: more crew & more alert on-watch crew (arguably, good reasons not to bother with a preventer), racing closer to the jibe, keeping lots of sail area up & more boat motion (just asking for a jibe!). Sounds to me like a judgement call, and your experience is suggesting for those conditions & your crew, a preventer was the wiser choice.

My wife & I are doing frequent offshore sails right now, and I rig a sidedeck boom vang and reef down conservatively to avoid having to deal with situations like the one you had to tackle. And at night, even more so! I know our circumstances don''t equate to offshore racing...but perhaps to some degree, they should. Thankfully, we didn''t hear you say anything about crew injuries...which would even more strongly suggest a preventer of some kind would have been a good idea.


EscapeArtist 06-15-2001 12:20 PM

Boom Preventer or Not?
I''m mulling over installing a brake.

I usually rig a temporary preventer by moving the boom vang from the mast down to the toe rail. It''s not a great solution, though.

The manufacturer claims that I can tighten the brake to the point where it''s a preventer.

John Rousmaniere has written many Sailnet articles where he discusses preventers and brakes. He is a vociferous supporter of their use, always, on any point of sail. You should read them.

cditzen 06-15-2001 03:29 PM

Boom Preventer or Not?
Hi Jack,

thanks for the reply. Yep, nobody got injured, and after the initial scaryness of the situation, everything turned out fine. We do have a vang (hydraulic), which isn''t easily moveable, so can''t double as a preventor.

In general, I think that rigging a preventor when running during long legs, esp. at night when crew fatigue sets in, seems like a really good idea. The one thing I am worried about is what happens during a broach??? I hate the idea of saving one thing just to run the risk of loosing the rig.


cditzen 06-15-2001 03:57 PM

Boom Preventer or Not?
Hello EscapeArtist,

thanks for pointing me to John''s article. Just found it. Hm, I am wondering about the puller-outer that he describes. Has anybody here used this thing successfully? If I understand correctly, you''d ease the spinny sheet during an accidental gybe to permit the boom to come (supposedly slowly?) across. I guess if the crew on spin-trim is too slow in that, I''d tear the foot of the chute (probably lot''s weaker than the force on the main). Any thoughts/comments?


jack_patricia 06-15-2001 05:18 PM

Boom Preventer or Not?
Chris, your wariness about setting a preventer and then broaching with the chute up is understandable. But you''ve kinda answered your own question, in that you''d probably change the point of sail a bit (to protect against the broach) if you weren''t racing. This is where I just don''t get it re: racing: to be competitive, you must sail the rhumb line but to sail the rhumb line, you recognize it will make the boat less safe.

Offshore but not racing, it sounds like you''d both change the point of sail a bit AND rig a preventer, no?

Jack, a racing wimp, I guess

JeffH 06-16-2001 08:30 PM

Boom Preventer or Not?
For offshore cruising I like the idea of having a dedicated system to run a preventer. In my mind the only acceptable method to rig a preventer is a line on each side of the boom, taken from the end of the boom, outside everything to a snatch block near the bow and then back to a cam cleat in the cockpit. The line should be comparatively light and stretchy; perhaps 1/4" or 3/8" three strand nylon. The long length of libe running from the boom ot bow to the stern allows for a lot of stretch and keeps the loads on the gooseneck and mast comapratively small ven if you dip the boom in the water or do a death roll. The use of a cam cleat is so that the preventor can be allowed to run without leaving the cockpit in the even of needing a quick and safe release.

For the kind of short legs that most of us do when we are out daysailing or weekending, a preventor is probably not the best idea because we often need to be able to jibe quickly due to traffic or to avoid grounding or hitting an obstruction. I think that using the vang as a preventor by bringing it to the deck or rail is just plain dangerous and probably more dangerous than an accidental jibe.


paulk 06-17-2001 05:19 PM

Boom Preventer or Not?
Sounds like Jeff''s idea would have saved the life of a sailor I knew who was knocked overboard by the boom while racing one night off Florida. The sea has different ways of pointing out unseamanlike conduct. Losing your binnacle comes across as a cheap lesson. What if the helmsman had been snared with it as well?

cditzen 06-19-2001 10:50 AM

Boom Preventer or Not?
Well, I just got back from delivering the boat back up to SF from Monterey. It was a phantastic 2 days of sailing, ending with a nice run into the bay to Berkeley, where we keep the boat.

This time, I rigged a preventor, from the end of the boom to a hefty eye amidships (typically used for the afterguy blocks). I used 10.5mm dynamic climbing rope I had. This is great stuff in that it''s build to give a bit (e.g. absorb a fall and not tear the bolts out of a wall). This setup seems to have worked great. The only improvement missing is to run the end of the line through a cam-cleat instead of tying it off as I did, which really isn''t fast enough to undo.
One question: has anybody ever tried to make this a double-ended system by using a block at the end of the boom instead of tying a knot there? Pros/Cons?


JeffH 06-19-2001 07:24 PM

Boom Preventer or Not?
Double ended? Where would you have the two ends?

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